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/*-
* Copyright (c) 2012 Dag-Erling Smørgrav
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: openpam_readword.c 588 2012-04-08 11:52:25Z des $
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <security/pam_appl.h>
#include "openpam_impl.h"
#include "openpam_ctype.h"
#define MIN_WORD_SIZE 32
/*
* OpenPAM extension
*
* Read a word from a file, respecting shell quoting rules.
*/
char *
openpam_readword(FILE *f, int *lineno, size_t *lenp)
{
char *word;
size_t size, len;
int ch, comment, escape, quote;
int serrno;
errno = 0;
/* skip initial whitespace */
comment = 0;
while ((ch = getc(f)) != EOF && ch != '\n') {
if (ch == '#')
comment = 1;
if (!is_lws(ch) && !comment)
break;
}
if (ch == EOF)
return (NULL);
ungetc(ch, f);
if (ch == '\n')
return (NULL);
word = NULL;
size = len = 0;
escape = quote = 0;
while ((ch = fgetc(f)) != EOF && (!is_ws(ch) || quote || escape)) {
if (ch == '\\' && !escape && quote != '\'') {
/* escape next character */
escape = ch;
} else if ((ch == '\'' || ch == '"') && !quote && !escape) {
/* begin quote */
quote = ch;
/* edge case: empty quoted string */
if (openpam_straddch(&word, &size, &len, 0) != 0)
return (NULL);
} else if (ch == quote && !escape) {
/* end quote */
quote = 0;
} else if (ch == '\n' && escape && quote != '\'') {
/* line continuation */
escape = 0;
} else {
if (escape && quote && ch != '\\' && ch != quote &&
openpam_straddch(&word, &size, &len, '\\') != 0) {
free(word);
errno = ENOMEM;
return (NULL);
}
if (openpam_straddch(&word, &size, &len, ch) != 0) {
free(word);
errno = ENOMEM;
return (NULL);
}
escape = 0;
}
if (lineno != NULL && ch == '\n')
++*lineno;
}
if (ch == EOF && ferror(f)) {
serrno = errno;
free(word);
errno = serrno;
return (NULL);
}
if (ch == EOF && (escape || quote)) {
/* Missing escaped character or closing quote. */
openpam_log(PAM_LOG_ERROR, "unexpected end of file");
free(word);
errno = EINVAL;
return (NULL);
}
ungetc(ch, f);
if (lenp != NULL)
*lenp = len;
return (word);
}
/**
* The =openpam_readword function reads the next word from a file, and
* returns it in a NUL-terminated buffer allocated with =!malloc.
*
* A word is a sequence of non-whitespace characters.
* However, whitespace characters can be included in a word if quoted or
* escaped according to the following rules:
*
* - An unescaped single or double quote introduces a quoted string,
* which ends when the same quote character is encountered a second
* time.
* The quotes themselves are stripped.
*
* - Within a single- or double-quoted string, all whitespace characters,
* including the newline character, are preserved as-is.
*
* - Outside a quoted string, a backslash escapes the next character,
* which is preserved as-is, unless that character is a newline, in
* which case it is discarded and reading continues at the beginning of
* the next line as if the backslash and newline had not been there.
* In all cases, the backslash itself is discarded.
*
* - Within a single-quoted string, double quotes and backslashes are
* preserved as-is.
*
* - Within a double-quoted string, a single quote is preserved as-is,
* and a backslash is preserved as-is unless used to escape a double
* quote.
*
* In addition, if the first non-whitespace character on the line is a
* hash character (#), the rest of the line is discarded.
* If a hash character occurs within a word, however, it is preserved
* as-is.
* A backslash at the end of a comment does cause line continuation.
*
* If =lineno is not =NULL, the integer variable it points to is
* incremented every time a quoted or escaped newline character is read.
*
* If =lenp is not =NULL, the length of the word (after quotes and
* backslashes have been removed) is stored in the variable it points to.
*
* RETURN VALUES
*
* If successful, the =openpam_readword function returns a pointer to a
* dynamically allocated NUL-terminated string containing the first word
* encountered on the line.
*
* The caller is responsible for releasing the returned buffer by passing
* it to =!free.
*
* If =openpam_readword reaches the end of the line or file before any
* characters are copied to the word, it returns =NULL. In the former
* case, the newline is pushed back to the file.
*
* If =openpam_readword reaches the end of the file while a quote or
* backslash escape is in effect, it sets :errno to =EINVAL and returns
* =NULL.
*
* IMPLEMENTATION NOTES
*
* The parsing rules are intended to be equivalent to the normal POSIX
* shell quoting rules.
* Any discrepancy is a bug and should be reported to the author along
* with sample input that can be used to reproduce the error.
*
* >openpam_readline
* >openpam_readlinev
*
* AUTHOR DES
*/
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